The objective of this application is to further characterize newly identified Stem Cells derived from root Apical Papilla (SCAP) and explore the potentiality of using SCAP along with periodontal ligament stem cells (PDLSCs) to regenerate root/periodontal tissue in the edentulous region by regular clinical dental implant procedures in a minipig model. We have recently isolated human SCAP and found their distinct properties from other dental stem cells such as dental pulp stem cells (DPSCs). In particular, SCAP show an increased dentin regeneration capacity in vivo, a distinct gene expression profile, and detectable levels of telomerase activity. Our preliminary studies imply that SCAP are early stem progenitors responsible for root formation, suggesting that SCAP may have advantages to be utilized for dental tissue regeneration. Before SCAP are considered for any clinical application, it is critical to understand their stem cell properties in depth. Very recently, we published part of our preliminary data to demonstrate that autologous SCAP and PDLSCs are capable of generating root/periodontal ligament tissues in the socket of newly extracted tooth to serve as a supporter to install porcelain crown in minipigs. However, this early "proof of principle" evidence does not represent regular clinical implant procedures. Therefore, we propose to explore potential of using SCAP and PDLSCs to regenerate root/periodontal tissues in the edentulous region mimicking clinical dental implant therapies. This approach may provide critical evidence for potential clinical application in the future. [unreadable] [unreadable] In this application, we will characterize multipotent differentiation of human and minipig SCAP and then utilize minipig SCAP and PDLSCs, a stem cell population capable of forming periodontal tissue, to cooperatively regenerate root/PDL complex. The reason of selecting minipigs for root/periodontal tissue regeneration is due to their similarity to humans in terms of their orofacial tissue structures and characteristics of dental stem cells. We will use molecular, cellular, histological, immunological, and stem cell transplantation approaches to characterize human SCAP and minipig SCAP/PDLSCs. The final goal of this proposed study is to explore potential of utilizing two populations of dental stem cells to reconstruct biologic root/periodontal complex in a pre-clinical model. We anticipate that our proposed studies in this R21 application will lead to a R01 application in the future. [unreadable]